The resolution of the lens seems to be quite low. According to www.photozone.de the lens performs much better than, for example, the 17-85 lens. Also user reports indicate that the 17-55 is better than the cheaper lenses.

Therefore, I wonder whether you got a bad lens which performs relatively bad. Since build quality differs this might easily be the case.

Hello and welcome to the forums - how do you pronounce ___ by the way?!

Photozone uses different tests to us, so I'm not surprised to find different results. Even when sites use the same charts though, differences in lighting and analysis can still deliver varying results - and as you quite rightly point out, there are good and bad copies of lenses.

We tested the same 17-55mm lens on both the 350D and 400D, and while our 400D group test shows the 17-85mm slightly outresolving it in the middle at f8, this doesn't mean it's a better lens overall. You only have to look at the corner performance to see the 17-55mm take the lead over the 17-85. You may also find the 17-55mm performing better at smaller focal ratios such as f4-f5.6.

I'm certainly not disappointed by the 17-55mm results in any way - I think it's a superb lens and a great option if you're into low-light photography.

"Photozone uses different tests to us, so I'm not surprised to find different results."

Agreed. But you say *simplified* that the 17-85 is good and that the 17-55 is good. Others say that the 17-55 plays in a completely different league and is much better than the 17-85. Therefore, I am wondering whether there are even better samples of the 17-55 (compared to the one you got).

Example: according to photozone the center resolution @24mm/ f8 for the 17-55 is 2053 (at f 5.6 it's even better). By contrast, the respective center resolution for the 17-85 is only 1909.